Medical balloon with radiopaque end portion for precisely identifying a working surface location

ABSTRACT

A balloon catheter comprises an elongated, tubular shaft extending in a longitudinal direction, said shaft having a proximal end and a distal end. An inflatable balloon is supported along the distal end of the shaft, the balloon when inflated including a generally cylindrical barrel section forming a working surface, and generally conical end sections that do not form a part of the working surface. The balloon further includes at least one radiopaque identifier for indicating the relative position of the working surface, said identifier being provided on at least one of the conical end sections of the balloon so as to define the extent of the working surface. Related aspects are also disclosed.

The following U.S. Provisional Patent Applications are incorporated by reference: 61/608,852; 61/608,859; 61/608,862; 61/608,897; 61/608,902; 61/608,908; 61/608,913; 61/608,917; 61/608,927; 61/608,932; 61/608,941; and 61/747,444.

TECHNICAL FIELD

This disclosure relates generally to balloons for performing medical procedures, such as angioplasty and, more particularly, to a medical balloon having a predetermined portion, such as a working surface, that may be precisely located or identified during use.

BACKGROUND OF THE INVENTION

Balloons are routinely used to resolve or address flow restrictions or perhaps even complete blockages in tubular areas of the body, such as arteries or veins. In many clinical situations, the restrictions are caused by hard solids, such as calcified plaque, and require the use of high pressures to compact such blockages. Commercially available balloons employ complex technology to achieve high pressure requirements without sacrificing the profile of the balloon. Besides high pressure requirements, the balloons should also be resistant to puncture, easy to track and push, and present a low profile, especially when used for angioplasty.

In clinical practice, angioplasty balloons are expanded from a deflated, folded state to an expanded state within a vessel to treat a target area, such as a portion of the circumferential inner wall I of a blood vessel V, as shown in FIGS. 1 and 2. The inflation of a balloon 12 with wall 28 is traditionally completed using an X-ray contrast agent CM along dimension DX to provide better visibility under X-ray or other form of radiography R during the interventional procedure, as illustrated in FIGS. 3 and 3 a (which shows the intensity measured by a fluoroscope detector plate, FDP). Typically, a 70/30 percent mixture of contrast agent and saline is used to inflate the balloon during an angioplasty procedure.

In general, a desirable goal is to reduce inflation and deflation times required for balloons without sacrificing the profile of the balloons, especially for large volume balloons (which can require up to two minutes of inflation/deflation times with the contrast agent). Because of its relatively high viscosity, it would also be desirable to eliminate, or at least reduce the amount of, the contrast agent used in inflation/deflation of the balloons. The use of contrast agent prolongs the inflation/deflation times and also poses the risk of iodine exposure to patients sensitive to iodine. In this regard, a non-radiopaque substance could be used in lieu of the contrast agent, such as for example saline or carbon dioxide, but such substances are invisible during X-ray imaging, and thus do not enhance visibility.

Furthermore, the physician performing the angioplasty procedure should be able to locate the position of the uninflated balloon with accuracy, so that the balloon will be properly positioned once inflated. This is conventionally accomplished by attaching marker bands on the catheter shaft in the region corresponding to the balloon working surface. This “working surface” is the surface along the portion of the balloon that is used to achieve the desired treatment effect, such as contacting the calcified plaque (which surface in the case of a balloon having conical or tapering portions at the proximal and distal ends is typically co-extensive with a generally cylindrical barrel section).

Misalignment of the marker bands during placement along the shaft sometimes results in their failure to correspond precisely to the extent of the working surface, as is shown in FIG. 4 (note misalignment amount X between each interior marker band M carried by shaft S and working surface W of balloon 12, which also typically includes a radiopaque tip P at the distal end). Even upon exercising great care to position the markers properly on the underlying shaft in alignment with anticipated boundaries of the working surface when the balloon is inflated, there remains a tendency for mismatch due to several possible factors. One such factor may be the tolerance stack-ups arising as a consequence of the affixation of the balloon to the distal end of the catheter shaft. The balloon also has a tendency to grow in the longitudinal direction when inflated, especially with large and particularly long balloons. Another factor is the tendency of the portion of the catheter shaft within the balloon to bend or flex during inflation. This may lead to misalignment between radiopaque markers fixed to the shaft and the working surface.

Whatever the cause, the resulting misalignment may prevent the clinician from accurately identifying the location of the working surface of the balloon during an interventional procedure. This may lead to a geographic misplacement, or “miss,” of the intended contact between the target area T and the working surface W of the balloon 12 (see FIG. 2). It is especially desirable to avoid such an outcome when the balloon is designed to deliver a payload (such as a drug, stent, or both) or a working element to a specified location within the vasculature, since a miss may prolong the procedure (such as, for example, by requiring redeployment of the balloon 12 or the use of another balloon catheter in the case of a drug coated balloon).

Upon deflation, the balloon may also be subject to a phenomenon known as “pancaking.” In this condition, the balloon 12 folds down upon itself to a flattened state, as shown in FIG. 5. This situation may cause the balloon to be viewed through fluoroscopy as perhaps still being in the inflated condition, since the full width of the balloon may be perceived in the flattened state. This can give the clinician the false perception that the balloon remains inflated, when in fact it is not.

Accordingly, the need is identified for a balloon for which the working surface may be identified during an interventional procedure with enhanced precision. The solution would take into account the possible mismatch between fixed locations on the catheter shaft and the balloon to define the working surface, and would operate independent of the position of the portion of the catheter shaft within the balloon. The improved identification may also allow for the better detection of the false perception of deflation caused by pancaking. Overall, procedural efficiency would be enhanced without remarkably increasing cost or complexity, and in a manner that can be applied to many existing catheter technologies without extensive modification.

SUMMARY OF THE INVENTION

An object of the disclosure is to provide a balloon for which the working surface may be identified during an interventional procedure with enhanced precision.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-9 are illustrative of the background of the invention;

FIG. 10 illustrates a first embodiment according to the disclosure;

FIG. 11 illustrates a second embodiment according to the disclosure;

FIG. 12 illustrates a third embodiment according to the disclosure;

FIG. 13 illustrates a fourth embodiment according to the disclosure;

FIG. 14 illustrates a fifth embodiment according to the disclosure;

FIG. 15 illustrates a sixth embodiment according to the disclosure;

FIG. 16 illustrates a seventh embodiment according to the disclosure;

FIG. 17 illustrates an eighth embodiment according to the disclosure; and

FIG. 18 illustrates the embodiment of FIG. 17 in a folded condition,

MODES FOR CARRYING OUT THE INVENTION

The description provided below and in regard to the figures applies to all embodiments unless noted otherwise, and features common to each embodiment are similarly shown and numbered.

Provided is a catheter 10 having a distal portion 11 with a balloon 12 mounted on a catheter tube 14. Referring to FIGS. 6, 7, and 8, the balloon 12 has an intermediate section 16, or “barrel,” and end sections 18, 20. In one embodiment, the end sections 18, 20 reduce in diameter to join the intermediate section 16 to the catheter tube 14 (and thus sections 18, 20 are generally termed cones or cone sections). The balloon 12 is sealed at balloon ends (proximal end 15 a and distal end 15 b) on the cone sections 18, 20 to allow the inflation of the balloon 12 via one or more inflation lumens 17 extending within catheter tube 14 and communicating with the interior of the balloon 12.

The catheter tube 14 also includes an elongated, tubular shaft 24 forming a guidewire lumen 23 that directs the guidewire 26 through the catheter 10, and along the distal end of which the balloon 12 may be located. As illustrated in FIG. 8, this guidewire 26 may extend through the proximal end of the catheter 10 and a first port 25 of a connector 27 into the lumen 23 to achieve an “over the wire” (OTW) arrangement, but could also be provided in a “rapid exchange” (RX) configuration, in which the guidewire 26 exits a lateral opening 14 a closer to the distal end (see FIG. 9) or else is fed through a passage associated with the tip P distally of the balloon 12 (“short” RX; not shown). A second port 29 may also be associated with catheter 10, such as by way of connector 27, for introducing a fluid (e.g., saline, a contrast agent, or both) into the interior compartment of the balloon 12 via the inflation lumen 17.

Balloon 12 may include a single or multi-layered balloon wall 28 forming the interior for receiving the inflation fluid. The balloon 12 may be a non-compliant balloon having a balloon wall 28 that maintains its size and shape in one or more directions when the balloon is inflated. Examples of non-compliant balloons may be found in U.S. Pat. No. 6,746,425 and Publication Nos. US 2006/0085022, US 2006/0085023 and US 2006/0085024, the disclosures of which are hereby incorporated herein by reference. The balloon 12 in such case also has a pre-determined surface area that remains constant during and after inflation, also has a pre-determined length and pre-determined diameter that each, or together, remain constant during and after inflation. However, the balloon 12 could be semi-compliant or compliant instead, depending on the particular use.

In order to provide for enhanced locatability during an interventional procedure, the balloon 12 may have a radiopaque quality. In one embodiment, this radiopaque quality is provided in a manner that allows for a clinician to differentiate, with relative ease and high precision, one portion of the balloon 12 from another (such as the barrel section 16 including the working surface W from the cone sections 18, 20). This helps the clinician ensure the accurate positioning of the balloon 12 and, in particular, the working surface W, at a specified treatment location, which may be especially important in the delivery of drugs via the balloon surface, as outlined in more detail in the following description.

In one embodiment, the radiopaque quality is achieved by providing strategically positioned identifiers, such as a plurality of at least partially radiopaque markings 30, at one or more locations along the balloon 12 to create a defined portion as the working surface W. The term “marking” as used herein denotes an indicia applied to the balloon wall 28, without interrupting the substantially continuous nature of the working surface W to help ensure an even treatment effect (which may be especially important, again, when the balloon 12 is one designed for the delivery of a drug to a particular treatment location).

As shown in FIGS. 10-12 and 14, this marking 30 may be provided in the form of a pair of markings 30, including a first strip 32 a located at the proximal end of the working surface W, and a second strip 32 b provided at the distal end of the working surface W. In other words, the first and second strips 32 a, 32 b, are provided with their outer edge proximally or distally, as the case may be, in alignment with the point at which the barrel section 16 transitions to form the cone sections 18, 20. The strips 32 a, 32 b may be provided in the form of narrow, elongated bands that extend around the entire circumference of the balloon 12 at the desired location(s) (including possibly at a medial portion of the working surface W, which helps the clinician to confirm the full inflation of the balloon 12).

In any case, the marking 30 is provided in a manner that does not require making the entire working surface W radiopaque, and also in a manner that does not prevent the working surface W from making full contact with the treatment area in the intended fashion (i.e., the marking 30 does not appreciably increase the diameter of the balloon 12, including when inflated). Likewise, the marking 30 is separate from any inner member extending within the interior compartment of the balloon 12, such as the shaft 24 forming the guidewire lumen 23.

The balloon 12 with markings 30 in this embodiment may be created in various ways. For example, the markings 30 may be provided by applying a radiopaque material to the wall 28 at the desired location in the form of a coating. This may be done by inking, spraying, printing, stamping, painting, adhering, or otherwise depositing (such as by chemical vapor deposition) the radiopaque material onto the balloon wall 28 (possibly with the application of a mask or the like, in which case the techniques of dipping or rolling the balloon 12 in the radiopaque material to form the desired coating could be used). Additionally or alternatively, the identifier providing the desired radiopacity may be embedded in the wall 28, including for example by providing it as a material layer of the wall 28, or in a single layer of adhesive between multiple layers that together form the wall 28. The marking 30 may be provided during the process for fabricating the balloon wall 28, such as for example during a co-extrusion or blow molding process. Examples of such techniques are described in co-pending applications filed on the same date as this application, including applications entitled “PARISON FOR FORMING BLOW MOLDED MEDICAL BALLOON WITH MODIFIED PORTION, MEDICAL BALLOON, AND RELATED METHODS,” for inventors Paul Fillmore, Andrew Schaffer, Allen Ronan, and Eoin Ryan, and “MEDICAL BALLOON WITH COEXTRUDED RADIOPAQUE PORTION,” for inventors Paul Fillmore, Justin Hall, Pat Byrne, and Margo Underwood. The disclosures of these applications are incorporated herein by reference.

In this or any other embodiment, the marking 30 is provided along a portion of the balloon 12 other than on or along the working surface W, which may include no radiopaque identifier or marking of any kind. For example, as shown in FIG. 11, the marking 30 may be provided only on one or both of the cone sections 18, 20 of the balloon 12. In the illustrated embodiment, the marking 30 is provided along the end sections 18, 20 up to the location in the longitudinal or axial direction where the working surface W begins and ends (e.g., the points where the cone sections 18, 20 transition to the barrel section 16 at the proximal and distal ends), which may be considered boundaries or edges.

In this or other embodiments, the marking 30 may extend along a portion of the cone sections 18, 20, or as shown in FIG. 12, may extend along the entire end or cone section 18, 20, or at least to the point where it is attached to the catheter tube 14 (and thus may provide an indication of the overall balloon length L). In either case, no portion of the catheter 10 associated with the working surface W (including the underlying shaft 24), includes an added radiopaque marker, element or material. Consequently, the entire working surface W is clearly differentiated from the portion of the balloon 12 including the radiopaque marking 30 or markings, and also readily differentiated from the full length L of the balloon 12.

In FIG. 13, it is shown that a radiopaque quality may be provided so as to create an accurate indication of the overall balloon length L to make the balloon 12 locatable without regard to any marker or the like on the tube 14 forming the inflation lumen 17 or the shaft 24 forming the guidewire lumen 23. This may be accomplished by providing the radiopaque identifier in the form of a marking 30 at or adjacent each of the locations where the balloon 12 terminates, such as for example at the proximal and distal ends 15 a, 15 b or even on the adjacent tube 14. This marking 30 may comprise strips in the form of circumferential bands 34 a, 34 b, similar to the markings in the form of strips 32 a, 32 b discussed previously in respect to one embodiment, and may be applied in the same manner. As shown in FIG. 14, the strips 32 a, 32 b (whether on the cone sections 18, 20 or barrel section 16) and bands 34 a, 34 b may also be used together to allow for the clear and precise identification of both the ends of the balloon 12 and the working surface W, as well as the balloon length L (see FIG. 13).

The balloon 12 may also be provided with radiopaque identifiers that differ between the cone sections 18, 20 and the barrel section 16. Thus, as shown in FIG. 15, the barrel section 16 may include a plurality of markings 30 comprising, for example, a first pattern (e.g., diagonal strips 37). Additionally or alternatively, one or both of the cone sections 18, 20 may include a second pattern, which may be different from the first pattern (e.g., circles 39), thus providing an indication of the working surface W. As should be appreciated, it is also possible to provide only one or both of the cone sections 18, 20 with the selected pattern, such that the barrel section 16 (and thus the working surface W) remains substantially non-radiopaque, or in any event includes no added radiopacifier.

Likewise, one or more of the markings 30 may take other forms of indicia, such as a logo O or alphanumeric information (such as a brand, trademark information, model or item number, catalog number, rated burst pressure, balloon length, balloon diameter, or the like), which again may be provided on the barrel section 16, cone sections 18, 20, or any combination. This identifier may be provided in a manner such that it can be perceived in the deflated state, or such that it may be read and understood when the balloon 12 is inflated or expanded, or both. In addition to helping define the location of the working surface W, this may also allow the clinician to verify or confirm that the correct balloon has been used and that it was successfully deployed or inflated. Still another possibility is to provide graduated radiopaque markings, such as a rule, gradations, or a scale, that indicate the relative dimensions of the balloon 12 on inflation, which may be checked externally for confirmation, if necessary or desired (such as by using a LEMAITRE tape, a version of which is distributed under the VASCUTAPE brand).

Turning to FIGS. 16 and 17, it can be understood that the identifier may be in the form of one or more radiopaque markings extending longitudinally along only one or both of the cone sections 18, 20 of the balloon 12, either along the entire cone section 20, as shown, or only partially. For example, as shown in FIG. 16, a single longitudinally extending strip 38 a may extend between the distal end 15 b of the balloon 12 and the distal edge or boundary of the working surface W. Alternatively, as shown in FIG. 17, a plurality of such strips, including but not limited to three strips 38 a, 38 b, 38 c may be provided. Plural strips may be spaced in the circumferential direction, and may have a greater spacing adjacent to the working surface W than at the ends 15 a or 15 b of the balloon 12 (at which point, the strips may actually converge and contact each other). The use of a plurality of strips, such as three 38 a, 38 b, 38 c, along one or both of cone sections 18, 20 may allow the clinician to be better able to detect the existence of pancaking, since the strips 38 a, 38 b, 38 c appear to be farther apart when the balloon 12 is inflated or flattened (pancaked), and closer when the balloon 12 is deflated (12′) and not flattened (compare FIGS. 17 and 18).

Balloons 12 that carry one or more surface elements, such as a payload (drug, stent, or both) or a working implement (cutter, focused force wire, or the like) into the vasculature may also benefit from the foregoing description of marking techniques. For example, as shown in FIG. 10, a balloon 12 including a defined working surface W, such as by providing radiopaque markings 30 at the transitions between the barrel section 16 and cone sections 18, 20, may include a portion coated with such a drug D, such as one designed for achieving a desired therapeutic effect when applied to the interior of the vessel. The radiopaque marking 30 may also correspond to the location of the drug D on the balloon 12, such as along the entire working surface W or only a portion of it. The drug D may be applied to the inflated balloon as part of the manufacturing process, and prior to folding for insertion in the vasculature. The clinician may thus with the benefit of a fluoroscope determine the precise positioning of the working surface W prior to inflating the balloon 12 in the vasculature to deliver the drug D to the desired location and provide the desired treatment regimen.

Examples of radiopaque materials include, but are not limited to, finely divided tungsten, tantalum, bismuth, bismuth trioxide, bismuth oxychloride, bismuth subcarbonate, other bismuth compounds, barium sulfate, tin, silver, silver compounds, rare earth oxides, and many other substances commonly used for X-ray absorption. The amount used may vary depending on the desired degree of radiopacity.

The identifiers may also comprise a radiopaque material applied to the interior surface of the balloon wall 28, such as by painting or other bonding. In one example, the radiopaque material comprises gold applied to the interior or exterior surface of the balloon 12, such as in the form of a band (which may be any of the bands described herein). The gold may be applied in leaf form, given its softness and malleability, which also means that it will not in any way hinder the expansion of the balloon 12.

The subject matter of each of the paragraphs below citing a balloon or a catheter can be part of a balloon or a catheter respectively that is cited in any of the other paragraphs:

1.1 A balloon catheter, comprising: an elongated, tubular shaft extending in a longitudinal direction, said shaft having a proximal end and a distal end; and an inflatable balloon supported along the distal end of the shaft, the balloon when inflated including first and second spaced conical end sections and a working surface between the conical sections, the balloon further including at least one radiopaque marking identifying the transition from the conical end section to the working surface. 1.2 The catheter of paragraph 1.1, wherein the at least one radiopaque marking comprises a first radiopaque marking at a first transition between the first conical end section and the working surface, and further including a second radiopaque marking at a second transition between the second conical end section and the working surface. 1.3 The catheter of any of the foregoing paragraphs, wherein the at least one marking comprises a strip. 1.4 The catheter of any of the foregoing paragraphs, further including a plurality of radiopaque markings in the form of strips. 1.5 The catheter of paragraph 1.4, wherein the strips extend at least partially in a longitudinal direction between the first and second conical end sections. 1.6 The catheter of paragraphs 1.4 or 1.5, wherein the strips comprise annular bands. 1.7 The catheter of any of the foregoing paragraphs, wherein at least two spaced radiopaque markings are provided on each conical end section, including one adjacent a distal portion and a proximal portion of each conical end section. 1.8 The catheter of any of the foregoing paragraphs, wherein the balloon includes a barrel section between the first and second conical end sections, and further including a plurality of radiopaque markings on the barrel section. 1.9 The catheter of any of the foregoing paragraphs, wherein the marking comprises a first pattern on the conical end sections and further including a second, different pattern on the working surface. 1.10 The catheter of any of the foregoing paragraphs, wherein the at least one marking is selected from the group consisting of a pattern, a strip, a brand, a logo, a letter, a number, a word, or combinations thereof. 1.11 The catheter of any of the foregoing paragraphs, wherein the identifier comprises a scale. 1.12 The catheter of any of the foregoing paragraphs, wherein the balloon includes a drug. 1.13 The catheter of paragraph 1.12, wherein the drug corresponds to the location of the radiopaque marking. 1.14 The catheter of paragraph 1.12, wherein the drug corresponds to other than the location of the radiopaque marking. 1.15 The catheter of paragraph 1.12, wherein the radiopaque marking comprises the drug formulated to include a radiopacifier. 1.16 A balloon having a drug carried on a working surface of the balloon wall and a radiopaque identifier identifying the location of the drug on the balloon. 1.17 The balloon of paragraph 1.16, wherein the radiopaque identifier comprises a radiopaque material mixed with a formulation comprising the drug. 1.18 The balloon of paragraph 1.16, wherein the working surface is along a barrel section of the balloon, and the radiopaque identifier is on one or both cone sections of the balloon. 2.1 A balloon catheter, comprising: an elongated, tubular shaft extending in a longitudinal direction, said shaft having a proximal end and a distal end; and an inflatable balloon supported along the distal end of the shaft, the balloon when inflated including a generally cylindrical barrel section forming a working surface, and generally conical end sections that do not form a part of the working surface, the balloon further including at least one radiopaque identifier for indicating the relative position of the working surface, said identifier being provided on at least one of the conical end sections of the balloon so as to define the extent of the working surface. 2.2 The catheter of paragraph 2.1, wherein the identifier comprises a marking. 2.3 The catheter of paragraph 2.1 or 2.2, wherein a first marking is provided at a first transition between the first conical section end section and the working surface and a second marking is provided at a second transition between the second end section and the working surface. 2.4 The catheter of paragraph 2.2 or 2.3, wherein the marking comprises a strip. 2.5 The catheter of any of the foregoing paragraphs, wherein the identifier comprises a longitudinal strip extending between an end of the balloon and the barrel section. 2.6 The catheter of any of the foregoing paragraphs, further including a plurality of identifiers. 2.7 The catheter of paragraph 2.6, wherein each of the plurality of identifiers comprises a longitudinally extending strip. 2.8 The catheter of paragraph 2.6 or 2.7, wherein the identifiers comprise annular bands. 2.9 The catheter of paragraph 2.6 or paragraph 2.8 as dependent on paragraph 2.6, wherein the identifiers comprise longitudinally extending strips. 2.10 The catheter of any of the foregoing paragraphs 2.1 to 2.9, wherein at least two spaced radiopaque identifiers are provided on each end section. 2.11 The catheter of any of the foregoing paragraphs 2.1 to 2.10, further including at least one radiopaque identifier on the barrel section. 2.12 The catheter of any of the foregoing paragraphs 2.1 to 2.11, wherein the identifier is a first identifier comprising a first pattern, and further including a second identifier comprising a second, different pattern. 2.13 The catheter of any of the foregoing paragraphs 2.1 to 2.12, wherein the identifier includes at least one letter or number. 2.14 The catheter of any of the foregoing paragraphs 2.1 to 2.13, wherein the identifier comprises a logo. 2.15 The catheter of any of the foregoing paragraphs 2.1 to 2.14, wherein the identifier comprises a scale. 2.16 The catheter of any of the foregoing paragraphs 2.1 to 2.15, further including a drug on the balloon. 3.1 An inflatable balloon for use in connection with a catheter, comprising: an inflatable body including a working surface extending in a longitudinal direction between a first end and a second end, the body having at least one radiopaque identifier provided along the body for identifying at least a first end of the working surface, the radiopaque identifier having a first radiographic quality for identifying the location of the first end of the working surface and a second radiographic quality at a location other than at the first end of the working surface. 3.2 The balloon of paragraph 3.1, wherein the second radiographic quality is provided for identifying the second end of the working surface. 3.3 The catheter of paragraph 3.2, wherein the first radiographic quality and the second radiographic quality are substantially the same. 3.4 The balloon of paragraph 3.1, wherein the radiopaque identifier comprises a marking. 3.5 The balloon of paragraph 3.1, wherein the radiopaque identifier follows a generally helical path from the first end to the second end of the working surface. 3.6 The balloon of paragraph 3.1, wherein the identifier comprises a plurality of helical identifiers extending along the working surface. 3.7 The balloon of paragraph 3.1, wherein the identifier comprises a radiopaque filament. 3.8 The balloon of paragraph 3.7, wherein the filament is wound helically along at least a portion of the working surface of the balloon. 3.9 The balloon of any of the foregoing paragraphs 3.1 to 3.8, further including a drug on the balloon. 3.16 A balloon for use in connection with a catheter, comprising: a body having an outer surface and at least one winding extending along the outer surface of the balloon, said balloon having a radiopaque quality. 3.17 The balloon of paragraph 3.16, wherein the winding comprises a radiopaque filament. 3.18 The balloon of any of the foregoing paragraphs, wherein the radiopaque identifier comprises a helical pattern or a diamond pattern. 3.19 A catheter including the balloon of any of the foregoing paragraphs. 3.20 An inflatable balloon for use in connection with a catheter comprising a radiopaque identifier comprising a helical pattern or a diamond pattern. 4.1 A balloon catheter for use in connection with a guidewire, comprising: an elongated, tubular shaft extending in a longitudinal direction, said shaft having a proximal end and a distal end; an inflatable balloon supported along the distal end of the shaft, the balloon when inflated including first and second spaced ends and a working surface between the ends; and at least one wire including at least a radiopaque portion for identifying the location of working surface of the balloon. 4.2 The catheter of paragraph 4.1, wherein said wire comprises a material having a shape memory for adjusting between a first state and a second state. 4.3 The catheter of paragraph 4.1 or 4.2, wherein the at least one wire extends generally in the longitudinal direction. 4.4 The catheter of any of the foregoing paragraphs 4.1 to 4.3, wherein the radiopaque portion is elongated. 4.5 The catheter of any of the foregoing paragraphs 4.1 to 4.4, wherein the wire at least partially comprises a polymer. 4.6 The catheter of any of the foregoing paragraphs 4.1 to 4.5, wherein the at least one wire is at least partially elastic. 4.7 The catheter of any of the foregoing paragraphs 4.1 to 4.6, comprising: a plurality of wires extending generally in the longitudinal direction, at least one of the wires including at least a radiopaque portion for identifying the location of working surface of the balloon. 4.8 The catheter of any of the foregoing paragraphs 4.1 to 4.7, wherein at least one wire extends along an outer surface of the balloon. 4.9 The catheter of any of the foregoing paragraphs 4.1 to 4.8, wherein at least one wire extends along an inner surface of the balloon. 4.10 The catheter of any of the foregoing paragraphs 4.1 to 4.9, wherein at least one wire extends from the first end to the second end of the balloon. 4.11 The catheter of any of the foregoing paragraphs 4.1 to 4.10, wherein the radiopaque portion of at least one wire extends along a portion of the balloon corresponding to the working surface. 4.12 The catheter of any of the foregoing paragraphs 4.1 to 4.11, wherein the radiopaque portion of at least one wire extends along other than along the portion of the balloon corresponding to the working surface. 4.13 The catheter of paragraph 4.7 or any of paragraphs 4.8 to 4.12 as dependent on paragraph 4.7, wherein the wires are spaced substantially equidistantly around a circumference of the balloon. 4.14 The catheter of any of the foregoing paragraphs 4.1 to 4.13, wherein the wire includes a compliant or semi-compliant portion. 4.15 The catheter of any of the foregoing paragraphs 4.1 to 4.14, wherein at least one end of the at least partially radiopaque wire is attached to a bond connecting the balloon to the shaft. 4.16 The catheter of any of the foregoing paragraphs 4.1 to 4.15, further including a drug provided on the balloon. 4.17 The catheter of any of the foregoing paragraphs 4.1 to 4.16, wherein at least one wire at least partially comprises a material having a shape memory for adjusting between a first state and a second state. 4.18 The catheter of paragraph 4.2 or 4.17, wherein the shape memory material comprises NITINOL. 5.1 A balloon catheter adapted for use with a guidewire, comprising: an elongated, tubular shaft extending in a longitudinal direction, said shaft having a proximal end and a distal end; an inflatable balloon supported along the distal end of the shaft, the balloon when inflated including first and second spaced ends and a working surface between the ends; and an insert located within the interior compartment of the balloon, the insert including at least a radiopaque portion separate from the shaft. 5.2 The catheter of paragraph 5.1, wherein the insert is adapted for moving relative to the shaft. 5.3 The catheter of paragraph 5.1 or 5.2, wherein the insert extends from a first end of the balloon to one end of the working surface. 5.4 The catheter of any of the foregoing paragraphs 5.1 to 5.3, wherein the insert comprises a tube made at least partially of a radiopaque material. 5.5 The catheter of any of the foregoing paragraphs 5.1 to 5.4, wherein the insert comprises at least one finger. 5.6 The catheter of paragraph 5.5, wherein the finger includes a radiopaque end portion. 5.7 The catheter of any of the foregoing paragraphs 5.1 to 5.6, wherein the insert comprises a plurality of fingers adapted for moving from a retracted condition to an expanded condition when the balloon is inflated. 5.8 The catheter of any of the foregoing paragraphs 5.1 to 5.7, further including a retractable sheath at least partially covering the insert. 5.9 The catheter of any of the foregoing paragraphs 5.1 to 5.8, wherein the insert comprises a wire. 5.10 The catheter of paragraph 5.9, wherein the wire includes a radiopaque portion corresponding to the working surface. 5.11 The catheter of paragraph 5.10, wherein the wire extends from the first end to the second end of the balloon, and the radiopaque portion comprises an intermediate portion of the wire. 5.12 The catheter of paragraph 5.10 or 5.11, wherein the wire extends from the first end to the second end of the balloon, and the radiopaque portion comprises an end portion of the wire. 5.13 The catheter of any of the foregoing paragraphs 5.1 to 5.12, wherein at least one end of the insert is connected at a location where the balloon connects to the tubular shaft. 5.14 The catheter of any of the foregoing paragraphs 5.1 to 5.13, wherein the insert comprises an annular band. 5.15 The catheter of any of the foregoing paragraphs 5.1 to 5.14, wherein the insert includes perforations. 5.16 The catheter of any of the foregoing paragraphs 5.1 to 5.15, wherein the insert comprises a material having a shape memory. 5.17 The catheter of any of the foregoing paragraphs 5.1 to 5.16, further including a drug on the balloon. 6.1 A parison for being blow molded into a medical balloon for a catheter, comprising: a first tubular layer having a functional modification; and a second tubular layer adapted for bonding with the first tubular layer to form the blow molded balloon. 6.2 The parison of paragraph 6.1, wherein the first layer is external to the second layer. 6.3 The parison of paragraph 6.1, wherein the first layer is internal to the second layer. 6.4 The parison of any of the foregoing paragraphs, wherein the functional modification comprises a radiopaque strip. 6.5 The parison of paragraph 6.4, wherein the strip comprises a circumferential band. 6.6 The parison of paragraph 6.4 or 6.5, wherein the strip extends between a first end and a second end of the first layer. 6.7 The parison of any of the foregoing paragraphs, wherein the first tubular layer is spaced from the second tubular layer. 6.8 The parison of any of the foregoing paragraphs, wherein the functional modification is selected from the group consisting of an added radiopacifier, a surface pattern, an etching, one or more perforations, and combinations of the foregoing. 6.9 A medical balloon formed by the parison of any of the foregoing paragraphs, comprising: a tubular, inflatable body comprising a wall, the body including first and second generally conical ends and a generally cylindrical barrel section between the generally conical ends and providing a working surface. 6.10 The balloon of paragraph 6.9, wherein the first layer extends from the first end to the second end of the balloon. 6.11 The balloon of paragraph 6.9, wherein the first layer extends along only the working surface. 6.12 The balloon of any of paragraphs 6.9 to 6.11, wherein the first layer extends along an entire circumference of a portion of the wall. 6.13 The balloon of any of paragraphs 6.9 to 6.12, wherein the first layer extends along the full circumference of the wall. 6.14 The balloon of any of paragraphs 6.9 to 6.13, wherein the wall includes first and second spaced shoulders, and wherein the first layer is positioned between the shoulders. 6.15 The balloon of any of paragraphs 6.9 to 6.14, wherein the first and second layers both extend from a first end to a second end of the balloon. 6.16 The balloon of any of paragraphs 6.9 to 6.15, further comprising an at least partially radiopaque tube positioned over the barrel section and extending substantially along the working surface. 6.17 The balloon of paragraph 6.16, further including first and second shoulders adjacent the proximal and distal ends of the radiopaque tube. 6.18 The balloon of paragraph 6.16 or 6.17, wherein the entire tube is radiopaque. 7.1 A balloon catheter, comprising: an elongated, tubular shaft having a proximal end and a distal end; and a balloon positioned along the distal end of the shaft, a portion of a wall of the balloon partially comprising a coextruded radiopaque material. 7.2 The catheter of paragraph 7.1, wherein the radiopaque portion comprises at least one strip extending along a working surface of the balloon. 7.3 The catheter of paragraph 7.1 or 7.2, wherein the radiopaque portion comprises at least one strip extending along a full length surface of the balloon. 7.4 The catheter of any of paragraphs 7.1 to 7.3, wherein the radiopaque portion comprises at least one strip extending along a first cone section of the balloon. 7.5 The catheter of paragraph 7.4, wherein the radiopaque portion comprises at least one strip extending along a second cone section of the balloon. 7.6 The catheter of any of paragraphs 7.1 to 7.5, wherein the balloon includes a plurality of radiopaque portions. 7.7 The catheter of paragraph 7.6, wherein each of the plurality of radiopaque portions comprises a longitudinal strip. 7.8 The catheter of paragraph 7.7, wherein the strips extend at least along a working surface of the balloon. 7.9 The catheter of any of paragraphs 7.6 to 7.8, wherein the plurality of radiopaque portions are spaced apart in a circumferential direction. 7.10 The catheter of any of the foregoing paragraphs 7.1 to 7.9, wherein the balloon includes a barrel section and conical sections at each end of the barrel section, and wherein the radiopaque portion is provided on the barrel section. 7.11 The catheter of any of the foregoing paragraphs 7.1 to 7.10, wherein the balloon includes a barrel section and conical sections at each end of the barrel section, and wherein the radiopaque portion is provided on one or both of the cone sections. 7.12 The catheter of any of the foregoing paragraphs 7.1 to 7.11, wherein the radiopaque portion comprises a layer of the balloon wall. 7.13 The catheter of paragraph 7.12, wherein the layer comprises an inner layer. 7.14 The catheter of paragraph 7.12 or 7.13, wherein the layer comprises an outer layer. 7.15 The catheter of paragraph 7.14, wherein the outer layer is etched. 7.16 The catheter of any of paragraphs 7.12 to 7.15, wherein the balloon includes a barrel section and conical sections at each end of the barrel section, and the layer extends along the entire barrel section. 7.17 The catheter of any of paragraphs 7.12 to 7.16, wherein the balloon includes a barrel section and conical sections at each end of the barrel section, and the layer extends along the entirety of one or both of the conical sections. 7.18 The catheter of any of the foregoing paragraphs 7.1 to 7.17, wherein all portions of the wall comprise coextruded radiopaque material. 7.19 The catheter of any of the foregoing paragraphs 7.1 to 7.18, further including a drug on the balloon. 7.20 The catheter of any of the foregoing paragraphs 7.1 to 7.19, wherein the radiopaque material comprises ePTFE. 8.1 A balloon catheter, comprising: a shaft extending in a longitudinal direction, said shaft having a proximal end and a distal end, and supporting at least one radiopaque identifier; an inflatable balloon supported along the distal end of the shaft, the balloon when inflated including a working surface; and an actuator for aligning at least one end of the working surface with the at least one radiopaque identifier. 8.2 The catheter of paragraph 8.1, wherein the actuator includes a first position corresponding to a deflated state of the balloon and a second position corresponding to the inflated state of the balloon. 8.3 The catheter of paragraph 8.1 or 8.2, wherein the actuator comprises a spring. 8.4 The catheter of any of the foregoing paragraphs 8.1 to 8.3, wherein the spring comprises a leaf spring. 8.5 The catheter of any of the foregoing paragraphs 8.1 to 8.4, wherein the actuator comprises a plurality of springs spaced circumferentially about the catheter. 8.6 The catheter of any of the foregoing paragraphs 8.1 to 8.5, wherein a first portion of the actuator is fixed to the balloon and a second portion of the actuator is adapted for movement relative to the shaft. 8.7 The catheter of paragraph 8.6, wherein the first portion of the actuator is captured between two layers on the wall of the balloon. 8.8 The catheter of paragraph 8.6 or 8.7, wherein the shaft includes a channel for at least partially receiving the second portion of the actuator. 8.9 The catheter of any of the foregoing paragraphs 8.1 to 8.8, further including a stop for stopping the movement of the actuator. 8.10 The catheter of any of the foregoing paragraphs 8.1 to 8.9, wherein the radiopaque identifier comprises a marker attached to the shaft. 8.11 The catheter of any of the foregoing paragraphs 8.1 to 8.10, wherein the radiopaque identifier comprises an insert positioned within the interior compartment of the balloon. 8.12 The catheter of any of the foregoing paragraphs 8.1 to 8.11, wherein the actuator is a first actuator for aligning a distal end of the working surface with the radiopaque identifier, and further including a second actuator for aligning a proximal end of the working surface with the radiopaque identifier. 8.13 The catheter of paragraph 8.12, wherein each of the first and second actuators comprise a plurality of springs. 8.14 The catheter of any of the foregoing paragraphs, wherein the radiopaque identifier comprises a first marking and a second marking, and wherein the actuator is a first actuator for aligning a distal end of the working surface with the first marking, and further including a second actuator for aligning a proximal end of the working surface with the second marking. 8.15 The balloon catheter of any of the foregoing paragraphs 8.1 to 8.14, comprising: a shaft extending in a longitudinal direction, said shaft having a proximal end and a distal end, and supporting first and second radiopaque identifiers; a first actuator for aligning a first end of the working surface with the first radiopaque marking; and a second actuator for aligning a second end of the working surface with the second radiopaque identifier. 8.16 The balloon catheter of any of the foregoing paragraphs 8.1 to 8.15, comprising: a shaft for carrying the balloon, the shaft including at least one channel formed in an outer portion of a wall of the shaft; and an actuator having a first end connected to the balloon and a second end at least partially positioned in the channel. 8.17 The balloon catheter of any of the foregoing paragraphs 8.1 to 8.16, comprising: a shaft for carrying the balloon, the shaft including a plurality of channels formed in an outer portion of the wall of the shaft. 8.18 The catheter of paragraph 8.17, further including an actuator having a first end connected to the balloon and a second end positioned in at least one of the channels. 8.19 The catheter of any of the foregoing paragraphs 8.1 to 8.8, comprising: a spring connected to a wall of the balloon. 8.20 The catheter of paragraph 8.19, wherein the spring is at least partially radiopaque. 8.21 The catheter of paragraph 8.19 or 8.20, wherein the spring is connected to a conical section of the wall of the balloon. 8.22 The balloon catheter of any of the foregoing paragraphs 8.1 to 8.21, wherein the balloon includes a drug. 9.1 A balloon catheter for use with a guidewire, comprising: an elongated, tubular shaft extending in a longitudinal direction, said shaft having a proximal end and a distal end; an inflatable balloon connected to the distal end of the shaft, the balloon including a working surface; a radiopaque identifier for identifying the working surface; and a receiver adjacent the proximal end of the shaft and adapted for allowing the shaft to move relative to the receiver in at least the longitudinal direction. 9.2 The catheter of paragraph 9.1, wherein the shaft carries a stop, and the receiver further includes a recess for receiving the stop, said recess having a dimension in the longitudinal direction that is greater than a corresponding dimension of the stop. 9.3 The catheter of paragraph 9.2, further including a tube for supplying an inflation fluid to inflate the balloon, said tube being connected to the receiver and generally coaxial with the shaft, and wherein the stop forms a seal with the recess to prevent the inflation fluid from passing around the shaft. 9.4 The catheter of paragraph 9.3, wherein the seal comprises an O-ring arranged coaxially with the shaft. 9.5 The catheter of paragraph 9.1, wherein the radiopaque identifier is separate from the shaft. 9.6 The catheter of paragraph 9.5, wherein the radiopaque identifier comprises an insert positioned within the interior compartment of the balloon. 9.7 The catheter of paragraph 9.6, wherein the insert comprises a tubular sleeve arranged coaxially with the shaft. 9.8 The catheter of paragraph 9.6, wherein the insert comprises a first insert at a proximal end of the balloon and a second insert at a distal end of the balloon. 9.9 The catheter of paragraph 9.1, further including a guidewire for positioning in the shaft. 9.10 A hub for a balloon catheter having an elongated, tubular shaft extending in a longitudinal direction, said shaft having a proximal end and a distal end, and an inflatable balloon connected to the distal end of the shaft for being inflated by an inflation fluid, comprising: a body including a receiver for receiving a proximal portion of the shaft and adapted for allowing the shaft to move relative to the receiver in at least the longitudinal direction; and a stop for restraining the movement of the shaft relative to the body in the longitudinal direction. 9.11 The hub of paragraph 9.10, wherein the body includes a guidewire port arranged in communication with the receiver, and further including an inflation port for introducing the inflation fluid for inflating the balloon. 9.12 The hub of paragraph 9.10, wherein the receiver further includes a recess for receiving the stop, said recess having a dimension in the longitudinal direction that is greater than a corresponding dimension of the stop. 9.13 The hub of paragraph 9.12, wherein the stop forms a seal with the recess to prevent the inflation fluid from passing. 9.14 The hub of paragraph 9.10, wherein the stop comprises an O-ring. 9.15 A catheter including a guidewire shaft having a distal end connected to a balloon and at a proximal end mounted for sliding movement. 9.16 The catheter of any of the foregoing paragraphs, further including a drug on the balloon. 9.17 A catheter comprising a hub for receiving a proximal end of a guidewire shaft, the shaft being adapted to slidably move in a restrained manner relative to the hub. 10.1 A balloon catheter, comprising: an elongated tubular shaft having a proximal end and a distal end spaced apart in a longitudinal direction, the shaft along a distal portion including at least one radiopaque identifier, said distal portion being formed of a material resistant to elongation in the longitudinal direction; and an inflatable, non-compliant balloon extending over the distal portion of the shaft. 10.2 The catheter according to paragraph 10.1, wherein the balloon includes a generally cylindrical barrel section positioned between generally conical sections, said barrel section including a working surface having at least one edge aligned with the radiopaque identifier. 10.3 The catheter according to paragraph 10.2, wherein the radiopaque identifier comprises a first marker positioned at the at least one edge of the working surface, and further including a second marker positioned at the opposite edge of the working surface in the longitudinal direction. 10.4 The catheter according to paragraph 10.2, wherein each marker comprises a radiopaque band swaged to the distal portion of the shaft. 10.5 The catheter according to paragraph 10.1, wherein the distal portion of the shaft comprises a tube adapted for guiding a guidewire from a proximal end of the balloon to a distal end of the balloon. 10.6 The catheter according to paragraph 10.1, wherein at least the distal portion of the shaft comprises steel. 10.7 The catheter according to paragraph 10.1, wherein the shaft comprises steel. 10.8 The catheter according to paragraphs 10.6 or 10.7, wherein the steel shaft comprises a stainless steel. 10.9 The catheter according to paragraphs 10.7 or 10.8, wherein the steel shaft includes a spiral cut along a portion other than the distal portion covered by the balloon. 10.10 The catheter according to paragraphs 10.7 or 10.8, wherein the steel shaft comprises a polymer layer. 10.11 The catheter according to paragraph 10.10, wherein the polymer layer comprises an outer layer of the shaft. 10.12 The catheter according to paragraph 10.1, wherein the distal portion of the shaft comprises a polymer shaft including a braid or mesh. 10.13 The catheter according to paragraph 10.1, wherein the balloon includes a generally cylindrical barrel section positioned between generally conical sections, the distal portion of the shaft extending from a first end of a first conical section to a second end of a second conical section. 10.14 The catheter according to paragraph 10.1, wherein the non-compliant balloon comprises one or more inelastic fibers. 10.15 The catheter according to paragraph 10.1, wherein the non-compliant balloon comprises polyethylene terephthalate. 10.16 The catheter of any of the foregoing paragraphs 10.1 to 10.15, further including a drug on the balloon. 11.1 A balloon catheter, comprising: a shaft extending in a longitudinal direction and adapted for expanding from a compressed condition to an expanded condition in the longitudinal direction, the shaft supporting at least one radiopaque identifier; and an inflatable balloon positioned along the shaft, the balloon when inflated including a working surface for aligning with the radiopaque identifier in at least the expanded condition of the shaft. 11.2 The catheter of paragraph 11.1, wherein the expandable shaft comprises a first portion connected in tandem to an expandable element. 11.3 The catheter of paragraphs 11.1 or 11.2, wherein the expandable element comprises a spring. 11.4 The catheter of paragraph 11.3, wherein the spring comprises a coil spring. 11.5 The catheter of paragraphs 11.3 or 11.4, wherein the spring comprises a tension coil spring. 11.6 The catheter of paragraph 11.2, wherein the expandable element comprises a bellows. 11.7 The catheter of paragraph 11.2, wherein the expandable element comprises a fiber matrix. 11.8 The catheter of paragraph 11.7, further including a spring associated with the fiber matrix. 11.9 The catheter of any of paragraphs 11.2-11.8, wherein the expandable element is inside an interior compartment of the balloon. 11.10 The catheter of any of paragraphs 11.2-11.8, wherein the expandable element is outside an interior compartment of the balloon. 11.11 The catheter of any of paragraphs 11.2-11.10, wherein the expandable element connects to one end of the balloon. 11.12 The catheter of any of paragraphs 11.2-11.10, wherein the expandable element connects the first portion of the shaft to a second portion of the shaft. 11.13 The catheter of any of the foregoing paragraphs 11.1 to 11.12, wherein the shaft comprises an inflation lumen for delivering an inflation fluid to the balloon. 11.14 The catheter of any of the foregoing paragraphs 11.1 to 11.13, wherein the expandable shaft in at least a partially expanded condition a port for delivering the inflation fluid to the balloon, said port being closed when the shaft is in a non-expanded condition. 11.15 The catheter of any of the foregoing paragraphs 11.1 to 11.14, wherein the expandable shaft comprises a first expandable element connecting a first portion of the shaft to a second portion of the shaft, and further including a second expandable element connecting the second portion of the shaft to a third portion of the shaft. 11.16 The catheter of paragraph 11.15, wherein the first and second expandable elements comprise first and second coil springs. 11.17 The catheter of paragraph 11.16, wherein the first and second coil springs have different spring constants. 11.18 The catheter of any of the foregoing paragraphs 11.1 to 11.17, wherein the radiopaque identifier comprises a pair of spaced radiopaque markers, one positioned in alignment with a first end of the working surface and another positioned at a second end of the working surface. 11.19 The catheter of any of paragraphs 11.15-11.18, wherein the first and second expandable elements comprise a radiopaque material. 11.20 The catheter of any of the foregoing paragraphs 11.1 to 11.19, wherein the radiopaque identifier comprises a spring. 11.21 The catheter of paragraph 11.2, wherein the expandable element comprises a spring having a variable spring constant. 11.22 The catheter of any of the foregoing paragraphs 11.1 to 11.21, wherein the shaft comprises a guidewire lumen. 11.23 The catheter of any of the foregoing paragraphs 11.1 to 11.22, further including a passage adjacent the tip for receiving a guidewire external to the balloon. 11.24 The catheter of paragraph 11.2, wherein the first portion is adjacent a distal end of the shaft. 11.25 A balloon catheter, comprising: a shaft; a balloon; and an expandable element adapted for expanding in the longitudinal direction connecting the shaft to the balloon. 11.26 The catheter of paragraph 11.25, wherein the expandable element is selected from the group consisting of a spring, a bellows, a fiber matrix, or combinations of the foregoing. 11.27 The catheter of paragraph 11.25 or 26, wherein the expandable element comprises an encapsulated spring. 11.28 A balloon catheter comprising a balloon and an inflation lumen including an expandable element adapted for expanding in the longitudinal direction for providing a fluid to the balloon. 11.29 The catheter of any of paragraphs 11.25-11.28, wherein the expandable element comprises a radiopaque material. 11.30 The catheter of any of the foregoing paragraphs 11.1 to 11.29, further including a drug on the balloon. 12.1 A balloon catheter, comprising: an elongated, tubular shaft extending in a longitudinal direction, said shaft having a proximal end and a distal end; and a balloon having an inflation compartment formed a balloon wall including a working surface, and further including at least one chamber adjacent to the working surface adapted for receiving an identifier for identifying the location of the working surface. 12.2 The balloon catheter of paragraph 12.1, wherein the shaft includes a first lumen for supplying a fluid to the chamber. 12.3 The balloon catheter of paragraph 12.2, wherein the shaft includes a port between the first lumen and the chamber. 12.4 The balloon catheter of paragraph 12.2, wherein the shaft includes a second lumen for supplying a fluid to an interior compartment of the balloon. 12.5 The balloon catheter of paragraph 12.4, wherein the shaft includes a port between the second lumen and the interior compartment. 12.6 The balloon catheter of any of the foregoing paragraphs 12.1 to 12.5, wherein the identifier comprises a contrast agent. 12.7 The balloon catheter of any of the foregoing paragraphs 12.1 to 12.6, wherein the contrast agent comprises a material selected from the group consisting of a radiopacifier, polyvinyl acetate, cellulose, a fluid, a liquid, a solid, a powder, or combinations of the foregoing. 12.8 The balloon catheter of any of the foregoing paragraphs 12.1 to 12.7, wherein the chamber comprises a first chamber at a proximal end of the balloon, and further including a second chamber at a distal end of the balloon. 12.9 The balloon catheter of paragraph 12.8, wherein the second chamber is adapted for receiving the identifier from a lumen in the shaft in fluid communication with the first chamber via a port. 12.10 The balloon catheter of any of the foregoing paragraphs 12.1 to 12.9, wherein the chamber is generally annular. 12.11 The balloon catheter of any of the foregoing paragraphs 12.1 to 12.10, wherein the chamber is positioned between a transition from a barrel section to a conical section of the balloon and an end of the balloon. 12.12 The balloon catheter of any of the foregoing paragraphs 12.1 to 12.11, wherein the chamber is provided by a film attached to the balloon wall. 12.13 The balloon catheter of any of the foregoing paragraphs 12.1 to 12.12, wherein the chamber is embedded in the balloon wall. 12.14 The balloon catheter of any of the foregoing paragraphs 12.1 to 12.13, wherein the chamber is provided by a film extending between the balloon wall and an outer surface of the shaft.

While the disclosure presents certain embodiments to illustrate the inventive concepts, numerous modifications, alterations, and changes to the described embodiments are possible without departing from the sphere and scope of the present invention, as defined in the appended claims. For example, the ranges and numerical values provided in the various embodiments are subject to variation due to tolerances, due to variations in environmental factors and material quality, and due to modifications of the structure and shape of the balloon, and thus can be considered to be approximate and the term “approximately” means that the relevant value can, at minimum, vary because of such factors. Accordingly, it is intended that the present invention not be limited to the described embodiments, but that it has the full scope defined by the language of the following claims, and equivalents thereof. 

The invention claimed is:
 1. A balloon catheter, comprising: an elongated, tubular shaft extending in a longitudinal direction, said shaft having a proximal end and a distal end; and an inflatable balloon supported along the distal end of the shaft, the balloon when inflated including a generally cylindrical barrel section forming a working surface and generally conical end sections that do not form a part of the working surface, the balloon further including a plurality of radiopaque identifiers for indicating a relative position of the working surface, said plurality of radiopaque identifiers being provided on at least one of the generally conical end sections of the balloon so as to define an end of the working surface without being located on the working surface, wherein the plurality of radiopaque identifiers comprise strips which, when the balloon is inflated, have a greater spacing adjacent to the working surface than at an end of the balloon, at which point, the strips converge and contact each other.
 2. The balloon catheter of claim 1, wherein the plurality of radiopaque identifiers comprise a first marking provided at a first transition between a first of the generally conical end sections and the working surface and a second marking provided at a second transition between a second of the generally conical end sections and the working surface.
 3. The balloon catheter of claim 1, wherein the strips comprise longitudinal strips extending between the end of the balloon and the barrel section.
 4. The balloon catheter of claim 1, wherein each of the strips comprises a longitudinally extending strip.
 5. The balloon catheter of claim 1, wherein the plurality of radiopaque identifiers comprise at least two spaced radiopaque identifiers provided on each end section.
 6. The balloon catheter of claim 1, further including at least one additional radiopaque identifier on the barrel section.
 7. The balloon catheter of claim 1, further including a drug on the working surface of the balloon.
 8. A balloon catheter, comprising: an elongated, tubular shaft extending in a longitudinal direction, said shaft having a proximal end and a distal end; and an inflatable balloon supported along the distal end of the shaft, the balloon when inflated including a generally cylindrical barrel section forming a working surface and generally conical end sections that do not form a part of the working surface, the balloon further including a plurality of radiopaque identifiers for indicating a relative position of the working surface, said plurality of radiopaque identifiers being provided so as to define an end of the working surface without being located on the working surface, wherein the plurality of radiopaque identifiers comprise at least three radiopaque identifiers provided on each end section, the at least three identifiers appearing to be farther apart from each other when the balloon is inflated or flattened, and closer to each other when the balloon is deflated and not flattened. 